Multi-load tractor hitch system

ABSTRACT

A tractor includes a hitch system comprising spaced lower draft links carrying draft hooks at their distal ends and an upper center link in the form of an extensible and retractable hydraulic actuator and a drawbar. An inverted U-shaped arch member has opposite legs respectively pivotally connected to the draft links at locations intermediate the ends thereof by means establishing a horizontal transverse axis about which the arch member is swingable fore and aft. A swivel bracket including rollers is mounted for rolling movement along the transverse bight portion of the arch member between a stored position on one of the legs of the arch member and an operative position on the transverse bight portion of the arch member. The hitch structure may be arranged in a three-point hitch mode by suspending the center link-forming hydraulic actuator from the bight portion of the arch member by spring means and by connecting a draft hook to the end of the piston rod of the center link-forming actuator. The hitch structure may be arranged in a weight transfer mode by placing the swivel bracket in its operative position, by connecting the end of the piston rod of the center link-forming actuator to the bracket and by connecting a force transmitting member or link between the swivel bracket and the implement to be towed. The hitch structure includes draft responsive means for initiating automatic draft and weight transfer control, the draft responsive means being, in one embodiment, responsive to forces imposed on the lower draft links or on the drawbar and being responsive in a second embodiment to draft forces imposed on the center link-forming actuator.

United States Patent [1 1 Koch et al.

[ Feb. 12, 1974 [22] Filed:

[ MULTI-LOAD TRACTOR HITCH SYSTEM [75] Inventors: James Allan Koch,Hudson; Donald Leroy Henderson, Waterloo, both of Iowa [73] Assignee:Deere & Company, Moline, lll.

May 16, 1973 21 Appl. No.: 360,707

Related US. Application Data [62] Division of Ser. No. 293,436, Sept.29, 1972.

Folkerts 172/7 Primary Examiner-Stephen C. Pellegrino [57] ABSTRACT Atractor includes a hitch system comprising spaced lower draft linkscarrying draft hooks at their distal ends and an upper center link inthe form of an extensible and retractable hydraulic actuator and adrawbar. An inverted U-shaped arch member has opposite legs respectivelypivotally connected to the draft links at locations intermediate theends thereof by means establishing a horizontal transverse axis aboutwhich the arch member is swingable fore and aft. A swivel bracketincluding rollers is mounted for rolling movement along the transversebight portion of the arch member between a stored position on one of thelegs of the arch member and an operative position on the transversebight portion of the arch member. The hitch structure may be arranged ina three-point hitch mode by suspending the center link-forming hydraulicactuator from the bight portion of the arch member by spring means andby connecting a draft hook to the end of the piston rod of the centerlink-forming actuator. The hitch structure may be arranged in a weighttransfer mode by placing the swivel bracket in its 0perative position,by connecting the end of the piston rod of the center link-formingactuator to the bracket and by connecting a force transmitting member orlink between the swivel bracket and the implement to be towed. The hitchstructure includes draft responsive means for initiating automatic draftand weight transfer control, the draft responsive means being, in oneembodiment, responsive to forces imposed on the lower draft links or onthe drawbar and being responsive in a second embodiment to draft forcesimposed on the center link-forming actuator.

3 Claims, 12 Drawing Figures MULTI-LOAD TRACTOR HITCH SYSTEM BACKGROUNDOF THE INVENTION This is a division of application Ser. No. 293,436,filed Sept. 29, 1972.

The present invention relates to a hitch system for agriculturaltractors and more particularly relates to a hitch system convertibleamong various hitch or coupling modes for attaching fully-mounted,semimounted and towed vehicles to a tractor, the hitch system includingautomatic draft and weight transfer con trol.

Most of present day agricultural tractors are engineered for serving asthe propelling unit for diverse implements for performing tillage,planting, cultivating and harvesting operations. These implements runthe gamut of fully-mounted, semi-mounted and towed implements.Additionally, some of these implements include parts'adapted to bedriven by the tractor power take-off.

It has been found that for certain operations hitch control featuressuch as automatic draft and weight transfer are invaluable.

Thus, it is appreciated that in order to accommodate the attaching ofthe aforementioned diverse implements and to afford desirable hitchcontrol features that a tractor must be provided with a hitch systemhaving diverse coupling capabilities and having appropriate hitchcontrols respectively operable for every coupling mode.

While hitch systems are available which have multicoupling modecapabilities and have the desired controls, they often require thatmembers be added or subtracted from the hitchv system to convert it fromone coupling mode to another and many of these members are quite heavyand/or difficult to install. Further, in many hitch systems some designsare compromised in order to avoid conflicting parts either to the extentthat the hitch system does not operate entirely satisfactorily in somecoupling modes or to the extent that some coupling modes are left out ofthe design.

SUMMARY OF THE INVENTION According to theinvention, there is provided ahitch system having diverse, compatible hitch modes and includingappropriate hitch controls for each mode.

It is an object of the invention to provide a hitch system which iseasily manually convertible among hith modes. v

Another object is to provide a hitch system having a novel three-pointhitch mode. More specifically, it is an object to provide draft hooks atthe rear ends of each of the center and draft links of a three-pointhitch and to resiliently suspend the upper link from an invertedU-shaped arch member pivotally coupled to the draft links forfore-and-aft rocking, the resilient suspension biasing the center linkso as to keep the hook carried thereby engaged with the upper hitch partof an implement.

Still another object is to provide a hitch system, as aforementioned,which has a novel weight transfer hitch mode. More specifically, it isan object to provide a swivel bracket mounted for movement along theabove-mentioned U-shaped arch member and to which the center link of thethree-point hitch can be optionally connected; the center link being inthe form of an extensible and retractable hydraulic actuator.

Yet another object of the invention is to provide a hitch systemincluding novel hydraulic controls for automatically controlling thecenter link when the system is in the weight transfer mode, the controlin one embodiment being responsive to the draft forces either imposed onthe tractor drawbar or on the draft links and in a second embodimentbeing responsive to the draft forces imposed on the center link-fomiingactuator.

These and other objects will become apparent from the followingdescription taken together with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary side view,with portions omitted, showing a typical arrangement of a tractor havinga fully-mounted implement connected thereto, the hitch system being in athree-point hitch mode.

FIG. 2 is a view, partially in section, taken along the line 2-2 in FIG.1.

FIG. 3 is an enlarged perspective view of the hitch system shown in FIG.l but in addition showing a drawbar assembly.

FIG. 4 is a fragmentary rear end view of one of the draft hooks shown inFIG. 3.

FIG. 5 is a fragmentary side view of the upper draft link.

FIG. 6 is a fragmentary side view, with portions omitted, showing atypical arrangement of a tractor having a trailing implement connectedthereto, the hitch system being in a weight transfer hitch mode.

FIG. 7 is an enlarged perspective view of the hitch system shown in FIG.6 but in addition showing the drawbar assembly.

FIG. 8 is a side view of the swivel bracket.

. FIG. 9 is a front view of the swivel bracket shown in FIG. 8.

FIG. 10 is a view similar to FIG. 6 but showing the tractor connected toa power take-off driven implement.

FIG. 11 is a schematic of a typical hydraulic circuit used to controlthe tractor hitch system.

, FIG. 12 is a schematic of a modified hydraulic circuit used to controlthe extension and retraction of the center link of the hitch system. I

DESCRIPTION OF THE PREFERRED EMBODIMENT Illustrated in the drawings isthe rear portion of an agricultural tractor, designated in its entiretyby the reference numeral 10, including a body or chassis l2 supported bya pair of rear traction wheels, only one of which is shown at 14.

Referring now to FIG. 1, the tractor shown therein is provided with ahitch system having a structure arranged in a three-point hitch mode andbeing connected to an earth-working implement here represented as afully-mounted plow 16. The plow 16 is of conventional structureincluding a beam 20 to which a plurality of plow bottoms, only one beingshown at 22,-

are connected through means of respective standards 24. Secured to theforward portion of the beam 20 is a mast structure 26, of conventionaldesign, including an upper hitch part 28 and a pair of lower spacedhitch parts, only one being shown at 30. All of the hitching parts arecylindrical elements such as pins and rods or the like. The tractorhitch structure includes draft members which extend between the tractorbody 12 and the hitch parts 28 and 30.

Specifically, referring additionally to FIGS. 2-5, the hitch structureincludes a pair of lower, laterally spaced draft links 32 respectivelyincluding a pair of draft hooks 34 at their rear ends, the hooks 34including upwardly opening jaws 36 in which are received the lower hitchparts 30 of the plow mast. The draft links 32 have their forward endsconnected, as at ball-and-socket connectors 38, to a pair of clevises 40extending rearwardly from the opposite legs of an A-frame 42 secured tothe underside of the tractor body 12 by means to be described presently.Thus, the draft links 32 may be swung vertically about the connectors 38and for the purpose there is provided a pair of lift links 44respectively having one of their ends connected intermediate the ends ofthe draft links and having the other of their ends respectivelyconnected to a pair of crank arms, only one being shown at 46, the crankarms 46 being integral with the opposite lateral ends of a transverserockshaft 48 rotatably mounted in the body 12 and selectively rotatableby a one-way hydraulic actuator or rockshaft cylinder 50 (FIG. 11) alsolocated in the body 12.

The draft links 32 are held in a fixed spaced relationship relative toeach other by means of an inverted U- shaped arch member 52 havingopposite legs 54 connected at their free ends to the links 32 atopposite locations intermediate the ends of the links by a pair ofball-and-socket connections, required for adequate degrees of freedom,only one being shown at 56 (FIG. 3), the connections establishinghorizontal transverse pivot axis about which the member 52 is rockable.

A two-way hydraulic actuator 58 forms an upper center link of the hitchstructure and includes a rearwardly extending piston rod terminating ina clevis to which a draft hook 59 is connected by a vertical pin 60which permits the hook to swivel between cast stops on the clevis. Aleaf spring 62 acts to center the hook. The hook 59 includes an upwardlyopening jaw 64 in which is received the upper hitch part 28 of the plowmast. A pivot pin 65 connects the actuator cylinder end to the tractorbody.

As can best be seen in FIGS. 3 and 5, the actuator 58 extends beneathand is suspended from a transverse bight portion 66 of the member 52 bya compression spring assembly including a cylindrical cartridge 67secured to the rearward surface of the bight portion by a plurality ofbolts 68 and having a rod 69 received axially therein, the rod having acoil spring 70 disposed thereabout and having an upper head portionbearing on the spring and holding the latter against the bottom end ofthe cartridge. The lower end of the rod projects through the bottom endof the cartridge 67 and is pivotally connected, as at horizontal pin 71,to a swivel connection 72 fixed to the top of and arranged to swivelparallel to the axis of the actuator 58. Thus, when the above-describedhitch structure is detached from an implement, as shown in FIG. 3, thespring assembly supports the actuator 58 in a generally horizontalposition and affords flexibility whereby an operator can manipulate theactuator 58 to attach it to an implement hitch part. Also it is herenoted that the spring 70 in addition serves to keep the jaw 64 engagedwith an implement hitch part received therein. This is accomplished dueto the fact that the opening in the jaw 64 is spaced above the openingsin the jaws 36 a vertical amount chosen so as to be greater, when theactuator is freely suspended as in FIG. 3, than the vertical distance Xbetween the upper and lower hitch parts of an implement such as shown inFIG. 1. Thus, the spring is in compression once the hitch structure isconnected to an implement as shown in FIG. 1. It is here noted that thespring 70 becomes fully compressed within a distance chosen such as tomake it impossible for the actuator 58 to bounce low enough duringtransport, to become unhooked from the upper implement hitch part 28.

Also, it is here noted that the actuator 58 may be suspended from thearch member by resilient means other than the compression springassembly. For example, leaf or tension springs may be used. Further, itis to be noted that the actuator 58 need not be suspended from the archmember 52 but may be supported at the top thereof; and the jaw 64 mayopen downwardly with the vertical distance between the opening in thejaw 64 and the openings in the jaws 36, when the actuator is freelysupported by the arch member, being lesser than the vertical distance X,the resilient means then being arranged to bias the actuator downwardlyto its freely supported position.

Cooperating with the manipulatable actuator 58 to aid the operator inconnecting an implement such as the plow 16 to the actuator 58 and tothe lower draft links 32 are a pair of removable inserts 73 respectivelylocated in the bottoms of the openings in the jaws 36 of the draft hooks34. The inserts 73 respectively include central spherical bearingportions 74 seated in complementary surfaces appearing in the jawopenings at 76. The inserts 73 are respectively held in place by a pairof dowel pins 78 (only one shown) located in the jaws on opposite sidesof the openings and along respective fore-and-aft extending diameters ofthe bearing portions 74. Thus, the inserts 73 may undergo a limitedamount of rocking about the dowel pins 78 for permitting an operator tomore easily connect the hitch structure to the lower cylindrical hitchparts of an implement when such hitch parts are canted relative to thehorizontal. I

Referring now to FIG. 6, the tractor l0 shown therein is provided with ahitch structure arranged in a weighttransfer hitch mode and beingconnected to an earthworking implement, here represented as a trailingdisk harrow 80, it being noted that many parts of the hitch structureare identical to those previously described and they are given the samereference numerals.

The harrow 80 is of conventional structure and includes a main frame 82to which gangs of disks, one being shown at 84, are connected. A drafttongue 86 is pivoted to the forward end of the frame 82 and has a clevis88 at its forward end, the clevis 88 being connected to an aperturedcross bar 89 having opposite ends received in the openings of the jawsof the draft hooks 34. The tongue may be connected directly to drawbar'if drawbar has draft sensing capability as will be described below withreference to FIG. 10. Here shown pivotally connected intermediate theends of the tongue 86, as at 90, is the rear end of a force transmittinglink or member 92, which may have its rear end connected to the frame 82if desired. The forward end of the link 92 is pivotally connected, as atupright pin 94 (FIG. 7), to a rearwardly extending clevis portion of afirst pivot block 96. The clevis at the rearward end of the piston rodof the actuator 58 is pivotally connected, by means of a vertical pin(not shown), to the forwardly extending end of a second pivot block 98.As can best be seen in FIGS. 8 and 9, the pivot blocks 96 and 98 arepivotally connected to each other and to the downwardly extending legsof a first U-shaped part 99 of a swivel bracket 100 by means of ahorizontal pin 102. The U-shaped part 99 is in turn pivotally connectedto a second U-shaped part 104 by means of a pin 106 extending throughthe respective bight portions of the parts 99 and 104. The swivelbracket 100 further includes a pair of rollers 108 which are rotatablymounted on pins extending between and having their opposite ends locatedin the opposite legs of the second U-shaped part 104. When the swivelbracket 100 is in its operative position, shown in FIG. 7, the legs ofthe part 104 straddle the transverse bight portion 68 of the arch member52 and the rollers 108 engage the upper surface thereof. Accordingly, inorder to transfer more of the weight of the implement 80 to the tractor10, the actuator 58 is retracted to swing the arch member 52 forwardlywhich results in the force transmitting link 90 exerting an increasedupward force on the implement to cause an attendant increase in theportion of the weight of the implement supported by the tractor. In asimilar but reverse manner, the portion of the weight of the implement80 supported by the tractor can be diminished by extending the actuator58.

From the description above, it will be apparent that the hitch structurecan be easily converted from the three-point hitch mode, shown in FIG.3, to the weight transfer hitch mode shown in FIG. 7, by disconnectingthe end of the spring assembly rod 69 from the actuator 58, by removingthe bolts 68 to disconnect the spring cartridge 67 from the arch member52, by mounting the swivel block 100 in its operative position on thebight portion 66 of the arch member and by connecting the actuator 58and the force transmitting link 92 to the swivel bracket 100. It is herenoted that when not in use, the swivel bracket 100, along with the pivotblocks 96 and 98 may be placed in a stored position (not shown) on oneor the other of the legs of the arch member 52.

Referring now to FIG. 10, there is shown the tractor 10 with a hitchstructure arranged in a weight-transfer hitch mode similar to thearrangement in FIG. 6, but being connected to a trailing earth-workingor harvesting implement 110 of a type having a power take-off driventool or conveyor, or the like, (not shown). The implement 110 includes aforwardly extending power shaft 112 connected to a power take-off shaft114 at the rear of the tractor. The power shaft 112 is supportedgenerally vertically above a forwardly extending draft tongue 116. Inorder to ensure adequate working clearance for the'power shaft 1 12, thearch member 52 is held in an elevated position by the lower draft links32 and a clevis 118 at the forward end of the tongue 116 is connected toa rearwardly extending drawbar 120. As can best be seen in FIGS. 3 and7, the drawbar 120 is received in a fore-and-aft extending sleeve member122 which is pivotally connected to a drawbar frame 124, as at a pin 126(FIG. 3), for horizontal swinging movement. The sleeve member 122 issupported, adjacent its rear end, for movement along an arcuate rearportion 128 of the frame 124 by means of a roller-containing bracket130. The drawbar 120 may be permitted to pivot freely about the pin 126or a pair of stops 131 may be used to hold the drawbar fixed, as shownin FIG. 7, or contained between desired limits.

The drawbar frame 124 includes a pair of oppositely extending pins 132which are received in apertured ears 133 forming a part of the A-frame42. Draft forces are thus transferred from the drawbar 120 to the A-frame 42. Connected to the swivel bracket is a force transmittinglinkage 134 comprising a first link 136 having its forward end pivotallyconnected to the pivot block 96 and having a pair of straps,-only onebeing shown at 138, connected to its rear end, the straps 138 straddlingthe power shaft 112 and being connected to the draft tongue 116.

Thus, it can be appreciated that when the tractor is connected to animplement in the manner illustrated in FIG. 10 and the drawbar ispermitted to swing free, the lateral shifting movement of the swivelbracket 100 along the bight portion of the arch member 52 acts inconjunction with the drawbar to maintain a weight transfer relationshipbetween the tractor and the implement while at the same time permittingthe implement to trail the tractor during turns.

The extension and retraction of the rockshaft cylinder 50, for adjustingthe vertical disposition of the lower draft links 32 and the extensionand retraction of the actuator 58 for adjusting the fore-and-aftdisposition of the draft hook 60 or for initiating changes in weighttransfer, may be selectively controlled either manually orautomatically, the automatic control being in response to draft forcesimposed on the hitch structure. For the purpose of automatic control,the A- frame 42 is connected to the tractor body 12 by means including ahorizontal transverse elastic bar 140 located in a depending portion ofthe body 12 and having opposite terminal end portions received as at142, in the opposite lateral side portions of the A-frame. The forwardcorner of the A-frame is connected to the body 12 by a pin and slotmeans 144 so that the A-frame may undergo limited fore-and-aft movementas the opposite ends of the bar 140 deflect when load is applied to theA-frame by the lower draft links 32. Rearward and forward deflection ofthe ends of the elastic bar 140 correspondingly causes the centralportionof the elastic bar to deflect respectively forwardly andrearwardly. This movement of the elastic bar is used to actuate acontrol linkage including a signal lever 146 (FIG. 11) which is pivotedat 148 to the tractor body and has a lower end located in the path ofmovement of and biased against the central portion of the elastic bar140 by means of a light spring 150. The upper end of the lever 146 ispivotally connected at 152 to the lower end of a secondary lever 154,the upper end of which is linked to a hand lever 156. A midportion ofthe secondary lever 154 is linked, as at 158, to one end of an axiallyshiftable main valve 160. Connected to one side of the main valve are apump 162 and a reservoir 164 and connected to the other side are a pairof lines 166 and 168. The valve 160 is a three-position valve and has acentral neutral position, as shown in FIG. 11, wherein the lines 166 and168 are blocked from fluid communication with the pump and reservoir, afirst operative position to the right of the neutral position, whereinthe line 166 is connected to the pump and the line 168 is connected tothe reservoir, and a second operative position to the left of theneutral position, wherein the line 166 is connected to the reservoir andthe line 168 is connected to the pump. Connected to the lines 166 and168 is a manually controllable on-off valve 170 which is in turnconnected to the opposite work ports of the actuator 58. The valve 170is selectively shiftable between on and of positions for respectivelypermitting and interrupting the flow of fluid between the opposite endsof the actuator 58 and the lines 166 and 168. Similarly, a manuallycontrollable on-off valve 172 is connected to the line 168 and to thesingle work port of the rockshaft cylinder 50, the valve 172 beingselectively shiftable between on and off positions for respectivelyconnecting and interrupting the flow of fluid between the cylinder andthe line 168.

It is to be noted that the above-described draft sensing means isrepresentative of the many draft sensing means which could be used tosense draft loads in the lower links 32 or in the drawbar 120 and send asignal to operate the main valve 160 and that the draft links anddrawbar could just as well be provided with other resilient draftsensors or, for that matter, with hydraulic or electrical draft sensorswithout affecting the principles of the invention described herein.

Assuming that the hitch structure is in the three-point hitch mode shownin FIG. 3 and that the hydraulic control .are as shown in FIG. 11, theoperation of the above-described hitch structure is as follows. If it isdesired to connect the plow 16 to the hitch structure, the operator willfirst back the tractor into close proximity to the plow 16. If the upperand lower draft hooks 59 and 34 are not at a level below the level ofthe upper and lower hitch parts 28 and 30 of the plow mast, the operatorwill shift the on-off valve 172 to its on position and will manuallyshift the main valve 160 to the right to connect the rockshaft cylinder50 to exhaust thus permitting the draft links 32 to gravitate to a lowerposition and thus dispose the hooks 59 and 34 at a lower position. Thevalve 160 is then returned to neutral. Once the draft hooks are at alevel below the hitch parts 28 and 30, the operator will back thetractor until the openings in the hook jaws 36 are directly below thehitch parts. To connect the upper draft hook 59 with the upper hitchpart 28 of the plow mast, the operator will adjust the draft hook 59 toits appropriateforeand-aft disposition by shiftingthe on-off valves 170and 172 respectively to their on and off positions and by shiftingthemain valve 160 to the right or left to selectively extend or retractthe actuator 58. When the draft hook 59 is at the correct fore-and-aftlocation for engaging the jaw opening with the upper hitch part 28, theoperator then will shift the main valve 160to the left to connect thepump with the rockshaft cylinder 50 causing the latter to rotate therockshaft 48 resulting in the draft links 32 being raised by the liftlinks 44 and the draft hook 59 being engaged with the upper hitch part28 and the inserts 73 being engaged with the plow hitch parts 30. If thehitch parts 30 are canted to the horizontal at the time of hitching,they still will become completely seated in the inserts 73 since theinserts will pivot on the dowel pins 78. Once the hitch parts 30 areseated, any suitable latch means may be used to block the entrance tothe openings to the jaws 36 to prevent the hitch parts from becomingdislodged during operation. Engagement of the upper hook 59 with theimplement part 28 deflects the actuator 58 downwardly against theresistance of the spring 70 in order to engage the opening of the jaw 64with the part 28 since the actuator 58 is suspended from the arch member52 so as to locate the jaw opening at a level above an upper hitch partwhen the lower hitch parts are connected to the draft hooks 34. Once theupper hitch part 28 is received in the opening of the jaw 64, the springacts to bias the bottom of the opening against the hitch part.

Assuming the plow 16 to be in operation, the operator will normally havethe hydraulic controls positioned for automatic draft control with theon-off valve 170 being in its off position and with the on-off valve 172being in its on position. The soil resistance acting on the plow 16creates a draft force in the lower links 32, which force is imposed onthe A-frame 42 and causes the latter to move rearwardly, as permitted bythe pin and slot means 144, to deflect the ends of the elastic bar 140.When a predetermined draft load is exerted on the A-frame, and thus onthe ends of the bar 140, the midportion of the elastic bar will bedeflected far enough forwardly to permit the light spring 150 to pivotthe signal lever 146 and shift the control valve 160 leftwardly toconnect the pump to the rockshaft cylinder 50 to actuate the latter forraising the draft links 32 resulting in the lifting of the plow 16. Whenthe draft loads decrease to the preselected amount, the elastic bar 140straightens out and acts against the lever 146 to return the valve 160to its neutral position. Similarly, but in a reverse manner, therockshaft cylinder 50 is actuated to lower the plow 16 deeper into theground to increase the draft load when the draft loads imposed on theA-frame decrease below the preselected amount.

Assuming that the hitch structure is in the three-point hitch mode shownin FIG. 3, the hitch structure can quickly and easily be converted tothe weight transfer mode shown in FIG. 7. Specifically, to accomplishthe conversion, the operator will need only to disconnect theupper drafthook 60 from the actuator 58, to disconnect the spring cartridge 67 androd 69 respectively from the bight portion 66 and the swivel connection72 to move the swivel bracket from its stored position (not shown) onone of the legs of the arch member 52 to its operative position (FIG. 7)on the transverse bight portion 66 of the arch member and to thenconnect the actuator 58 to the swivel block.

The hitch structure is now in condition to be coupled to a. trailingimplement such as the disk plow 80 (FIG. 6) or a power take-off drivenimplement such as the implement (FIG. 10). Assuming that the hitchstructure is to be coupled to the disk plow 80, the clevis 88 of theplow may be connected, in the usual manner, either to the crossbar 89when seated in the openings of the lower draft hooks 34 or to thetractor drawbar after the tractor backed to dispose the crossbar 89 ordrawbar close to the clevis 88 of the disk tongue 86. The forcetransmitting link 92 will then be fastened between the tongue 86 and theswivel bracket 100 to complete the connection. This latter operation mayrequire the swivel bracket 100 to be adjusted fore-and-aft and suchadjustment is accomplished in the same manner described above relativeto the fore-and-aft adjustment of the upper draft hook 60.

When the disk harrow 80 is in operation, the operator will normallydesire automatic weight transfer control. To obtain this control, theon-off valve is shifted to its on position, the on-ofi valve 172concerning draft control then being in its off" position. Automaticweight transfer control is then accomplished in the same mannerdescribed above relative to automatic draft control. Specifically, draftloads are transferred to the Aframe 42 either through the draft links 32or the drawbar 120 and cause the elastic bar 140 to deflect in responseto draft forces which are above and below a predetermined force, toactuate the main valve 160 to respectively cause retraction andextension of the actuator 58 to increase and decrease the pull on theforce transmitting link 92 and cause a commensurate increase anddecrease in'the portion of the weight of the disk harrow 80 supported bythe tractor 10. The mounting of the swivel bracket 100 on the archmember 52 maintains a substantially constant relationship between theforce transmitting link 92 and the tongue 86 when the tractor 10 isturning since the bracket 100 will roll along the bight portion of thearch member in the direction of the turn.

With the hitch structure arranged in the weight transfer mode, thetractor 10 can be connected to an implement having a power take-offdriven tool or conveyor or the like such as the implement 1 10 in muchthe same manner described above relative to connecting the tractor tothe disk harrow 80. Now, however, the clevis at the forward end of thetongue 116 is connected only to the tractor drawbar 120 and thelowerdraft arms 32 are held elevated to provide adequate clearancebeneath the arch member 52 for the power shaft 112 which is connected tothe tractor power take-off 1114.

Referring now to FIG. 12, there is shown a modified control means forautomatically controlling the extension and retraction of the actuator58 in response to the draft load carried by the actuator 58 as reflectedby the pressure of the fluid in the rearward end of the actuator 58.Such a modified control is applicable to tractors which do not havemeans for sensing draft imposed on their lower draft links or theirdrawbars. Specifically, a pressure responsive, three-position controlvalve 174 is connected, at one side, to the pump 162 and the reservoirand, at its other side, to the opposite work ports of the actuator 58. Apilot line 176 interconnects the rearward end of the actuator cylinderwith a piston (not shown) at'the right end of the valve 174. Acting onthe left end of the valve 174 is a variable neutralizing spring 178 forholding the valve 174 in a neutral position, as shown, when apreselected pressure is acting on the valve 174. Thus, it is seen thatwhen increased draft loads cause the pressure in the rearward end of thecylinder of the actuator 58 to increase above the preselected pressure,the control valve 174 will shift to the left and connect the rearwardand forward ends of the actuator cylinder respectively to the reservoirand the pump resulting in the extension of the actuator 58. It followsthen that when the pressure in the rearward end of the cylinder of theactuator 58 falls below the preselected pressure, the valve 174 willshift rightwardly and connect the pump and reservoir to the actuator 58so as to cause the latter to retract. This has the efiect of maintaininga constant amount of weight transfer no matter that hill and swaleconditions are encountered.

Thus the control means shown in FIG. 12 does not require the A-frame 42,the elastic bar and the attendant control linkage shown in FIG. 11 and,therefore, may be used on a wide variety of tractors.

We claim:

1. For a tractor and trailing implement combination wherein the tractorhas hitch means including trailing lower draft links, a generallyupright member pivotally connected to the draft links for fore-and-aftrocking about a generally horizontal transverse axis and having an upperportion spaced above and extending transversely relative to the lowerdraft links, and an upper draft link having opposite ends respectivelypivotally connected to the tractor and the upper portion of the uprightmember, the implement having groundengaging means supporting the weightthereof and having a forwardly extending draft means connected to saidhitch means, a force transmitting member connected between the implementand the upper portion of the upright member, a hydraulic systemincluding an extendible and retractable hydraulic motor and controlmeans therefor, one of the upper draftlinks and force transmittingmembers incorporating said motor, the control means including draftsensing means incorporated in said hitch means for transmitting a signalrepresentative of draft loads imposed on the hitch means and includingvalve means coupled to said sensing means and responsive to signalstransmitted thereby for causing contraction of said motor fortransferring a selected portion of the implement weight to the tractor,the improvement comprising: the connection between the upper portion ofthe upright member and the upper link and the force transmitting memberincluding connection means mounted on said upper portion for movementtherealong.

2. The invention defined in claim 1 wherein the hitch means furtherincludes a drawbar pivoted to the tractor for generally horizontalswinging, and said implement draft member means being connected to thedrawbar.

3. The invention defined in claim 1 wherein said upper draft linkincorporates an extendible and retractable hydraulic motor; weighttransfer control means including a three-position pressure responsivevalve means for controlling the extension and retraction of saidhydraulic motor; a pilot line means connecting the fluid pressure in oneend of the motor with said valve means for shifting the valve means in afirst direction toward a first active position and biasing means actingon the valve means opposite to the first direction for shifting thevalve means to a second active position; and said biasing means andpilot pressure cooperating to hold the valve means in a neutral positionintermediate said first and second positions when a preselected pilotpressure exists in said pilot line means.

1. For a tractor and trailing implement combination wherein the tractorhas hitch means including trailing lower draft links, a generallyupright member pivotally connected to the draft links for fore-and-aftrocking about a generally horizontal transverse axis and having an upperportion spaced above and extending transversely relative to the lowerdraft links, and an upper draft link having opposite ends respectivelypivotally connected to the tractor and the upper portion of the uprightmember, the implement having ground-engaging means supporting the weightthereof and having a forwardly extending draft means connected to saidhitch means, a force transmitting member connected between the implementand the upper portion of the upright member, a hydraulic systemincluding an extendible and retractable hydraulic motor and controlmeans therefor, one of the upper draft links and force transmittingmembers incorporating said motor, the control means including draftsensing means incorporated in said hitch means for transmitting a signalrepresentative of draft loads imposed on the hitch means and includingvalve means coupled to said sensing means and responsive to signalstransmitted thereby for causing contraction of said motor fortransferring a selected portion of the implement weight to the tractor,the improvement comprising: the connection between the upper portion ofthe upright member and the upper link and the force transmitting memberincluding connection means mounted on said upper portion for movementtherealong.
 2. The invention defined in claim 1 wherein the hitch meansfurther includes a drawbar pivoted to the tractor for generallyhorizontal swinging, and said implement draft member means beingconnected to the drawbar.
 3. The invention defined in claim 1 whereinsaid upper draft link incorporates an extendible and retractablehydraulic motor; weight transfer control means including athree-position pressure responsive valve means for controlling theextension and retraction of said hydraulic motor; a pilot line meansconnecting the fluid pressure in one end of the motor with said valvemeans for shifting the valve means in a first direction toward a firstactive position and biasing means acting on the valve means opposite tothe first direction for shifting the valve means to a second activeposition; and said biasing means and pilot pressure cooperating to holdthe valve means in a neutral position intermediate said first and secondpositions when a preselected pilot pressure exists in said pilot linemeans.